$ { {2} \times \left[\begin{array}{rr}{3} & {1} \\ {-1} & {0}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{2}\times{3} & {2}\times{1} \\ {2}\times{-1} & {2}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{6} & {2} \\ {-2} & {0}\end{array}\right]}$